Colombians voted on Sunday for a successor to President Alvaro Uribe in an election pitting a veteran government minister who waged war on leftist rebels against an eccentric former mayor vowing to battle corruption, Reuters reported. Front-runners former Defense Minister Juan Manuel Santos and former Bogota Mayor Antanas Mockus both promise to maintain Uribe's security policies, but polls show neither can win the more than 50 percent needed to avoid a June runoff. A key U.S. ally in the region, Uribe steps down still popular after two terms dominated by his war against drug-trafficking rebels, and his pro-business approach that increased foreign investment five-fold. He was barred by a constitutional court from seeking a third term. Santos, one of Uribe's staunchest supporters, is tied in most polls with Mockus, the son of Lithuanian immigrants and a former university professor who surged in support with a Green party campaign against graft and "politics as usual." The two are also running close in opinion polls for the June 20 runoff. The four other main candidates are far behind. -- SPA